Capital Letters that are built-in symbols

Question

I'm trying to search for an answer to "What is the complete list of single capital letters that represent built-in Mathematica commands, symbols, or uses?"

For example:

C, D, E, I, N, O

Is this the complete list? I'm teaching linear algebra in the fall, and I will warn students about using variable names that start with capital letters, but I'd also like to be specific about which particular letters will cause a problem.

Try running Select[Names["System`*"], StringLength[#] == 1 && UpperCaseQ[#] && ! StringMatchQ[ToString[FullForm[#]], "*Formal*"] &]. — J. M.'s missing motivation, Jun 08 '16 at 05:16
Cases[Names["System`*"], Alternatives @@ CharacterRange["A", "Z"]] — Basheer Algohi, Jun 08 '16 at 05:38
@C. E., but not as it stands; I'll write something a bit longer later, unless you want to do so on my behalf. :) — J. M.'s missing motivation, Jun 08 '16 at 05:38
@J.M. how did you format your comment in code format. I couldn't do it with the context System` :( — Basheer Algohi, Jun 08 '16 at 05:39
@AHB it is there you can see it but it did not work becase we have one from the context System — Basheer Algohi, Jun 08 '16 at 05:41
I have edited your comment, @Algohi; the trick is to enclose any snippet with a backtick within two sets of backticks. — J. M.'s missing motivation, Jun 08 '16 at 05:41
@J.M. Aha, so I had previously three backticks. Got it. Thanks :) — Basheer Algohi, Jun 08 '16 at 05:42
However, note, that K is the only one among standard latin capitals that is not Protected. Also, some of the one-letter formal symbols are Systemsymbols, but not all: compareAttributes@{[FormalPhi], [FormalCurlyPhi]}` (see here). — István Zachar, Jun 08 '16 at 07:07

score 13 · Accepted Answer · answered Jun 08 '16 at 11:10

To convert my comment into an answer: one can naively run Select[Names["System`*"], StringLength[#] == 1 &] to pick out built-in symbols that are only one character long. This will work in older versions of Mathematica, but ever since the introduction of formal symbols (which are, to be fair, in the System` context and are one-character expressions as well), this needs to be finessed further. Thus, we must add extra criteria to filter out the classical list of reserved capital letters (as of the current version):

Select[Names["System`*"], StringLength[#] == 1 &&
                          UpperCaseQ[#] &&
                          StringFreeQ[CharacterName[#], "Formal"] &]
   {"C", "D", "E", "I", "K", "N", "O"}

A (more expensive) alternative uses the new entity framework through WolframLanguageData[] like so:

Select[WolframLanguageData[], StringLength[CanonicalName[#]] == 1 &] // CanonicalName
   {"N", "C", "I", "O", "D", "E"}

but this misses K, which is the arbitrary index used for explicit sums and products returned as solutions by symbolic functions (akin to the use of C as an arbitrary constant). (Try e.g. RSolve[x[k + 1] == x[k] Prime[k], x, k].)

AHB · Answer 2 · 2016-06-08T05:51:45.843

12

They are:

C D E I K N O

It's easy to know. Just open a notebook and type the capital alphabet. Those changing color to black are protected.

edited Jun 08 '16 at 05:51

answered Jun 08 '16 at 05:29

AHB

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It's also easy to remember: ONE D--- Never mind. – Peltio Jun 08 '16 at 05:37
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@Peltio, don't you start. :P – J. M.'s missing motivation Jun 08 '16 at 05:41
@AHB What does "type the capital alphabet" mean? I can't get this to work. – David Jun 08 '16 at 18:02
3

He's telling you to type each capital letter manually in each cell, @David. – J. M.'s missing motivation Jun 08 '16 at 18:26
@J.M Aha! I get it. Thanks to both of you. – David Jun 09 '16 at 04:08
@Peltio I'm so pure boy.When I realize this,your this comment come to my mind. :) – yode Jul 11 '16 at 18:28
@Peltio Although years have passed, I cannot still get your first comment. What did you mean? – AHB Apr 11 '18 at 18:29
@AHB this will take some creativity on your end, how to arrange the letters. – doublefelix Apr 24 '20 at 14:53
The code below takes 130 seconds on my computer to generate all possible Mnemonics that represent words. Be warned that Peltio's saucy word choice that he could not write hear appears in the list. – userrandrand Dec 23 '22 at 10:58
1

( Permutations[{"E","N","I","O","K","C","D"}] //Map[StringJoin] //Map[ Select[SpellingCorrectionList@#, x|->ContainsExactly[ DeleteCases[" "]@Characters@x, Characters@# ] ]& ] //DeleteDuplicates ) – userrandrand Dec 23 '22 at 10:58
Among the candidates, removing the not safe for stack exchange saucy ones, the most reasonable candidates are "INK CODE" "INK DECO" "ION DECK" and "COED INK" – userrandrand Dec 23 '22 at 11:05

score 8 · Answer 3 · answered Jun 09 '16 at 00:10

8

With a fresh kernel, use

Select[CharacterRange["A", "Z"], NameQ]

{"C", "D", "E", "I", "K", "N", "O"}

answered Jun 09 '16 at 00:10

kglr

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score 7 · Answer 4 · edited Jul 11 '16 at 18:19

7

Quiet[Select[CharacterRange["A", "Z"], Context[#] == "System`" &]]

{C, D, E, I, K, N, O}

Hope this can help.

edited Jul 11 '16 at 18:19

J. M.'s missing motivation

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answered Jun 08 '16 at 06:45

yode

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This did not work for me. I entered Select[CharacterRange["A", "Z"], UnsameQ[Context[#], $Context] &] and got things like: Context::notfound: Symbol A not found. >> and General::stop: Further output of Context::notfound will be suppressed during this calculation. >> even though I first quit the kernel. – David Jun 08 '16 at 18:00
In Mathematica 10.4 I needed to add ToExpression thus Select[ToExpression /@ CharacterRange["A", "Z"], UnsameQ[Context[#], $Context] &] – mikado Jun 08 '16 at 19:17
Sorry @David ,maybe I miss something yesterday.And I have a verification just now. – yode Jun 08 '16 at 23:45
@yode No need to be sorry. That worked. I totally appreciate your help. – David Jun 09 '16 at 04:05

Capital Letters that are built-in symbols

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